
Japanese kiryu medium grain size, 5-6 mm approx.
A slightly acidic mineral substrate of volcanic origin, with high hardness, which improves drainage and delays soil degradation.
When mixed with akadama, it is essential for pines, but it is also ideal in a mixture ratio of 20-30% for the vast majority of species, except for some basophilic plants, such as olive trees.
It has low water retention capacity, but excellent fertiliser retention due to the cation exchange it produces with it because of its chemical composition.